Note: Descriptions are shown in the official language in which they were submitted.
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SAMPLE MIXING ON A MICROFLUIDIC DEVICE
The present invention relates to the mixing of fluid samples in a microfluidic
sample processing device.
Sample processing devices including process chambers in which various chemical
or biological processes are performed play an increasing role in scientific
and/or
diagnostic investigations. The process chambers provided in such devices are
preferably
small in volume to reduce the amount of sample material required to perform
the
processes.
One persistent issue associated with sample processing devices including
process
chambers is in the mixing of materials in the process chambers. For example,
mixing may
be useful to improve utilization of reagents and/or sample utilization. Many
sample
processing devices are, however, designed to use small volumes of sample
material (e.g., 5
microliters) that are not easily accessed after loaded into the sample
processing devices
designed to process such small sample volumes.
SUMMARY OF THE INVENTION
The present invention provides mixing structures for use on sample processing
devices. The mixing structures include one or more mixing chambers in fluid
communication with a process chamber, such that changing the rotational speed
of the
sample processing device forces sample material into and out of the mixing
chamber to
achieve mixing of the sample material. The mixing chambers are in fluid
communication
with the process chambers through mixing ports that are located on the distal
sides of the
process chambers with respect to the axis about which the sample processing
device is
rotated.
One potential advantage of the mixing structures of the present invention is
that
mixing can still be performed even if the process chamber volume is larger
than the
sample volume. Mixing can still occur because rotation of a partially filled
process
chamber can still move sample material into the mixing chamber because the
mixing port
is located on the distal side of the process which is where the sample
material will be
driven during rotation of the sample processing device.
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In some embodiments, the process chambers may include exit ports that are also
located on the distal side of the process chambers. One potential advantage of
such a
construction may be, e.g., enhanced emptying of the mixing chambers and the
process
chambers.
In other embodiments, the mixing chamber may be located within the footprint
of
the process chamber. One potential advantage of such a construction is that
the area on
the sample processing device occupied by the process chamber and associated
mixing
structure can be reduced.
In one aspect, the present invention provides a sample mixing structure on a
sample processing device, the sample mixing structure including a process
chamber with a
delivery port on a proximal side of the process chamber and an exit port on a
distal side of
the process chamber; a mixing chamber with a mixing port, wherein the mixing
port is
located on the distal side of the process chamber. Rotation of the sample
processing
device about an axis of rotation moves at least a portion of sample material
in the
processing chamber into the mixing chamber through the mixing port when the
mixing
port is open, wherein the proximal side of the process chamber is located
closer to the axis
of rotation than the distal side of the process chamber. When the exit port of
the process
chamber is open, rotation of the sample processing device about the axis of
rotation moves
the sample material out of the process chamber and the mixing chamber.
In another aspect, the present invention provides sample mixing structure on a
sample processing device, the sample mixing structure including a process
chamber with a
delivery port on a proximal side of the process chamber and an exit port on a
distal side of
the process chamber, wherein the exit port is closed; and a mixing chamber
with a mixing
port, wherein the mixing port is located on the distal side of the process
chamber. The
process chamber is located between a first major side and a second major side
of the
sample processing device, wherein at least a portion of the mixing chamber is
located
between the process chamber and the second major side of the sample processing
device.
Rotation of the sample processing device about an axis of rotation moves at
least a portion
of sample material in the processing chamber into the mixing chamber through
the mixing
port when the mixing port is open, wherein the proximal side of the process
chamber is
located closer to the axis of rotation than the distal side of the process
chamber. When the
exit port of the process chamber is open, rotation of the sample processing
device about
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the axis of rotation moves the sample material out of the process chamber and
the mixing
chamber.
In another aspect, the present invention provides sample mixing structure on a
sample processing device, the sample mixing structure including a process
chamber with a
delivery port on a proximal side of the process chamber and an exit port on a
distal side of
the process chamber; a first mixing chamber in fluid communication with the
process
chamber through a first mixing port, wherein the first mixing port is located
on the distal
side of the process chamber; and a second mixing chamber in fluid
communication with
the process chamber through a second mixing port, wherein the second mixing
port is
located on the distal side of the process chamber. Rotation of the sample
processing
device about an axis of rotation moves at least a portion of sample material
in the
processing chamber into at least one of the first mixing chamber and the
second mixing
chamber, wherein the proximal side of the process chamber is located closer to
the axis of
rotation than the distal side of the process chamber. When the exit port of
the process
chamber is open, rotation of the sample processing device about the axis of
rotation moves
the sample material out of the first mixing chamber, the second mixing
chamber, and the
process chamber.
In another aspect, the present invention provides a method of mixing fluids in
a
sample processing device. The method includes providing a sample processing
device that
includes a process chamber, at least one mixing chamber, and at least one
mixing port
located on a distal side of the process chamber; providing sample material in
the process
chamber; rotating the sample processing device about an axis of rotation,
wherein at least
a portion of sample material in the processing chamber moves into the at least
one mixing
chamber through the at least one mixing port when rotating the sample
processing device,
wherein the rotating comprises at least one acceleration and deceleration
cycle.
In another aspect, the present invention provides a method of mixing fluids in
a
sample processing device. The method includes providing a sample processing
device
having a process chamber, at least one mixing chamber, and at least one mixing
port
located on a distal side of the process chamber; providing sample material in
the process
chamber; rotating the sample processing device about an axis of rotation,
wherein at least
a portion of sample material in the processing chamber moves into the at least
one mixing
chamber through the at least one mixing port when rotating the sample
processing device,
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wherein the rotating comprises two or more acceleration and deceleration
cycles. The
method also includes opening an exit port in the process chamber after
rotating the sample
processing device to move at least a portion of sample material in the
processing chamber
into the at least one mixing chamber; and removing at least a portion of the
sample
material from the process chamber through the exit port by rotating the sample
processing
device about the axis of rotation.
These and other features and advantages of the present invention may be
described
in connection with various illustrative embodiments of the invention below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of one exemplary sample processing device according to
the
present invention.
FIG. 2 is an enlarged view of one exemplary mixing structure and associated
process chamber according to the present invention.
FIG. 3 is an enlarged cross-sectional view of the process chamber of FIG. 2,
taken
along line 3-3 in FIG. 2.
FIGS. 4 & 5 depict mixing actions using a process chamber and mixing chamber
in
one embodiment of the present invention.
FIG. 6 is a perspective view of an alternative process chamber and associated
mixing structure according to the present invention.
FIG. 7 is a perspective view of another alternative process chamber and
associated
mixing structure according to the present invention.
FIG. 8 is an enlarged cross-sectional view of the process chamber and
associated
mixing structure of FIG. 7, taken along line 8-8 in FIG. 7.
DETAILED DESCRIPTION OF ILLUSTRATIVE
EMBODIMENTS OF THE INVENTION
In the following detailed description of illustrative embodiments of the
invention,
reference is made to the accompanying figures of the drawing which form a part
hereof,
and in which are shown, by way of illustration, specific embodiments in which
the
invention may be practiced. It is to be understood that other embodiments may
be utilized
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and structural changes may be made without departing from the scope of the
present
invention.
The present invention provides a sample processing device that can be used in
the
processing of liquid sample materials (or sample materials entrained in a
liquid) in
multiple process chambers to obtain desired reactions, e.g., PCR
amplification, ligase
chain reaction (LCR), self sustaining sequence replication, enzyme kinetic
studies,
homogeneous ligand binding assays, and other chemical, biochemical, or other
reactions
that may, e.g., require precise and/or rapid thermal variations. More
particularly, the
present invention provides sample processing devices that include one or more
process
arrays, each of which may preferably include a loading chamber, at least one
process
chamber, a valve chamber, and conduits for moving fluids between various
components of
the process arrays.
Although various constructions of illustrative embodiments are described
below,
sample processing devices of the present invention may be similar to those
described in,
e.g., U.S. Patent Application Publication Nos. US2002/0064885 A1 (Bedingham et
al.);
US2002/0048533 A1 (Harms et al.); US2002/0047003 A1 (Bedingham et al.); and
US2003/0138779 A1 (Parthasarathy et al.); as well as U.S. Patent No. 6,627,159
B1
(Bedingham et al.) and U.S. Patent Application No.lO/734,717, titled VARIABLE
VALVE APPARATUS AND METHODS, filed on December 12, 2003. The documents
identified above all disclose a variety of different constructions of sample
processing
devices that could be used to manufacture sample processing devices according
to the
principles of the present invention.
One illustrative sample processing device manufactured according to the
principles
of the present invention is illustrated in FIG. 1 which is a plan view of one
sample
processing device 10 that may include process chambers and associated mixing
structures
of the present invention. The sample processing device 10 may preferably be in
the shape
of a circular disc as illustrated in Figure 1, although any other shape that
can be rotated
could be used in place of a circular disc, e.g., rectangular, etc.
The sample processing device 10 includes at least one process array 20 as seen
in
FIG. 1. In other embodiments, it may be preferred that the sample processing
device 10
include two or more process arrays 20. If the sample processing device 10 is
circular as
depicted, it may be preferred that each of the depicted process array 20
includes
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components that are aligned with a radial axis 21 extending from proximate a
center 12 of
the sample processing device 10 towards the periphery of the sample processing
device
10. Although this arrangement may be preferred, it will be understood that any
arrangement of process arrays 20 on sample processing device 10 may
alternatively be
used.
The sample processing device 10 is designed to be rotated to effect fluid
movement
through the process array 20. It may be preferred that the axis of rotation
extend through
the center 12 of the sample processing device 10, although variations
therefrom may be
possible.
The process array 20 preferably includes at least one process chamber 40. In
the
depicted embodiment, the process array 20 also includes an optional loading
chamber 30
connected to the process chamber 40 along a conduit 32. The process chamber 40
may
preferably be connected to a second process chamber 50 connected to the first
process
chamber 40 along conduit 42. The process chamber 40 may preferably include a
valve 44
to control movement from the process chamber 40 to the secondary process
chamber 50.
The valve 44 may preferably be normally closed until opened. The process array
20 also
includes a mixing chamber 60 in fluid communication with the process chamber
40.
It should be understood that a number of the features associated with the
process
array 20 may be optional. For example, the loading chamber 30 and associated
conduit 32
may be optional where sample material can be introduced directly into the
process
chamber 40 through a different loading structure. Other optional features may
include,
e.g., the valve 40 and/or the secondary process chamber 50 and the conduit 42
leading to
it.
Any loading structure provided in connection with the process arrays 20 (e.g.,
loading chamber 30) may be designed to mate with an external apparatus (e.g.,
a pipette,
hollow syringe, or other fluid delivery apparatus) to receive the sample
material. The
loading structure itself may define a volume (as, e.g., does loading chamber
30 of FIG. 1)
or the loading structure may define no specific volume, but, instead, be a
location at which
sample material is to be introduced. For example, the loading structure may be
provided
in the form of a port through which a pipette or needle is to be inserted. In
one
embodiment, the loading structure may be, e.g., a designated location along a
conduit that
is adapted to receive a pipette, syringe needle, etc. The loading may be
performed
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manually or by an automated system (e.g., robotic, etc.). Further, the sample
processing
device 10 may be loaded directly from another device (using an automated
system or
/manually).
FIG. 2 is an enlarged plan view of the process chamber 40 and its associated
mixing structure in the form of a mixing chamber 60 and mixing port 62 through
which
the mixing chamber 60 is in fluid communication with the volume of the process
chamber
40.
It may be preferred that the mixing port 62 be located on the distal side of
the
process chamber 40 where the distal side of the process chamber 40 is defined
as that side
of the process chamber 20 that is located distal from the axis of rotation
about which the
sample processing device 10 is rotated to effect fluid movement through the
process array
and/or mixing using mixing chamber 60. As discussed herein, the axis of
rotation may
preferably be the center 12 of the sample processing device 10. In some
instances in
which sample material is delivered to the process chamber 40 through a conduit
32, the
15 distal side of the process chamber 40 may be defined as the side opposite
the delivery port
34 through which the sample material enters the process chamber 40. In such an
embodiment, the delivery port 34 may preferably be located in the proximal
side of the
process chamber 40, i.e., the side of the process chamber 40 that is closest
to the axis
about which the sample processing device 10 is rotated to effect fluid
movement.
20 The valve 44 depicted in FIG. 2 can be opened to allow sample material in
the
process chamber 50 to move into conduit 42 for delivery to the secondary
process
chamber 50. The valve 44 may take the form of a valve septum 46 provided in a
valve lip
48 overhanging a portion of the process chamber 40 as depicted in the cross-
sectional
view of FIG. 3. Further examples and discussions of such valve structures may
be found
in, e.g., U.S. Patent Application Publication No. US2003/138779 Al
(Parthasarathy et al.)
and U.S. Patent Application No. 10/734,717, titled VARIABLE VALVE APPARATUS
AND METHODS, filed on December 12, 2004.
Although sample processing devices of the present invention may be
manufactured
using any number of suitable construction techniques, one illustrative
construction can be
seen in the cross-sectional view of FIG. 3. The sample processing device 10
includes a
base layer 14 attached to a core layer 16. A cover layer 18 is attached to the
valve layer 16
over the side of the core layer 16 that faces away from the base layer 14.
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The layers of sample processing device 10 may be manufactured of any suitable
material or combination of materials. Examples of some suitable materials for
the base
layer 14 and/or core layer 16 include, but are not limited to, polymeric
material, glass,
silicon, quartz, ceramics, etc. For those sample processing devices 10 in
which the layers
will be in direct contact with the sample materials, it may be preferred that
the material or
materials used for the layers be non-reactive with the sample materials.
Examples of some
suitable polymeric materials that could be used for the substrate in many
different
bioanalytical applications may include, but are not limited to, polycarbonate,
polypropylene (e.g., isotactic polypropylene), polyethylene, polyester, etc.
It may be preferred that, in some embodiments, the core layer 18 be
transparent or
translucent such that the features formed in the core layer 16 and/or base
layer 14 may be
seen through the cover layer 18. For example, in the depicted embodiment of
sample
processing device 10, the core layer 18 does allow for visualization of the
features in the
process array 20 as described herein.
~ The layers making up sample processing device 10 may be attached to each
other
by any suitable technique or combination of techniques. Suitable attachment
techniques
preferably have sufficient integrity such that the attachment can withstand
the forces
experienced during processing of sample materials in the process chambers.
Examples of
some of the suitable attachment techniques may include, e.g., adhesive
attachment (using
pressure sensitive adhesives, curable adhesives, hot melt adhesives, etc.),
heat sealing,
thermal welding, ultrasonic welding, chemical welding, solvent bonding,
coextrusion,
extrusion casting, etc. and combinations thereof. Furthermore, the techniques
used to
attach the different layers may be the same or different. For example, the
technique or
techniques used to attach the base layer 14 and the core layer 16 may be the
same or
different as the technique or techniques used to attach the cover layer 18 and
the core layer
16.
By locating the mixing port 62 on the distal side of the process chamber 40,
changing the rotational speed of the sample processing device 10 can be used
to
selectively move sample material into and out of the mixing chamber 60.
Movement of
sample material into and out of the mixing chamber 60 from the process chamber
40 may
be useful to, e.g., mix the sample material with, e.g., a reagent 41 located
within the
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process chamber 40. Such a reagent 41 is depicted in the enlarged cross-
sectional view of
FIG. 3.
FIGS. 4 & 5 depict movement of sample material 70 into and out of mixing
chamber 60. In FIG. 4, the sample material 70 is located substantially within
process
chamber 40. The sample material 70 may have been delivered to the process
chamber 40
through, e.g., conduit 32 from loading chamber 30 through rotation of the
sample
processing device 10. Although the rotation of sample processing device 10 may
have
been sufficient to deliver the sample material 70 to the process chamber, the
centrifugal
forces developed by the rotation were not sufficient to cause the sample
material 70 to
enter the mixing chamber 60.
Once in position within process chamber 40 as seen in FIG. 4, however, the
mixing
port 62 leading to mixing chamber 60 is preferably closed off by the sample
material 70.
As a result, any air or other compressible fluid located within mixing chamber
60 is
entrapped therein.
If the sample processing device 10 is rotated faster such that the centrifugal
forces
on the sample material 70 increase, at least a portion of the sample material
70 is
preferably forced into the mixing chamber 60 through mixing port 62 as
depicted in, e.g.,
FIG. 5. The air or other compressible fluid (preferably a gas) located within
the mixing
chamber 60 is preferably compressed within the mixing chamber 60 due to the
centrifugal
forces acting on the denser sample material 70. Reducing the rotational speed
of the
sample processing device 10 may preferably return at least some, and perhaps
preferably
all of the sample material 70 to the process chamber 40.
If rotation is used to accomplish mixing according to the present invention,
the
rotation may preferably include at least one acceleration and deceleration
cycle, i.e., the
rotational speed of the sample processing device 10 may be increased to drive
at least a
portion of the sample material 70 into the mixing chamber 60 followed by
deceleration to
a lower rotational speed (or to a stop) such that at least a portion of the
sample material 70
moves out of the mixing chamber 60. In some instances, it may be preferred
that the
mixing involve two or more such acceleration and deceleration cycles.
Repeated movement of the sample material 70 into and out of the mixing chamber
60 by changing the rotational speed of the sample processing device 10 may
enhance
mixing of the sample materials 70 and any reagents located within the process
chamber
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40. Furthermore, in some instances, one or more reagents may be provided in
the mixing
chamber 60 such that contact of the sample material 70 with such reagents may
preferably
be controlled by changing the rotational speed of the sample processing device
10. For
example, the time of initial contact of the sample material 70 with reagents)
located in the
mixing chamber 60 may be controlled based on the rotational speed of the
sample
processing device 10.
FIG. 6 is another alternative embodiment of a process chamber and associated
mixing structure in accordance with the principles of the present invention.
In many
respects, the process chamber 140 and associated mixing structure are similar
to that
described in connection witli FIGS. 1-5. Among the differences are that the
mixing
structure is provided in the form of two mixing chambers 160a and 160b that
are in fluid
communication with the process chamber 140 through mixing ports 162a and 162b,
respectively.
The mixing chambers 160a and 160b (collectively referred to herein as mixing
chambers 160) may preferably be located on opposite sides of the radial axis
121 along
which process chamber 140 is located. As depicted, radial axis 121 may
preferably be an
axis of symmetry for the mixing chambers 160.
The process chamber 140 also includes a delivery port 134 through which sample
material may be delivered to the process chamber 140. The delivery port 134
may
preferably be located on the proximal side of the process chamber 140, i.e.,
the side of the
process chamber 140 that is closest to the axis about which the sample
processing device
containing process chamber 140 is rotated to effect fluid movement and/or
sample
material mixing using mixing chambers 160.
As seen in FIG. 6, the features (e.g., process chamber 140, mixing chambers
160,
delivery port 134, etc.) are formed in a core layer 116 to which a base layer
114 is
attached. In the actual device, a cover layer (not shown) is provided over the
major
surface of the core layer 116 that is opposite the major surface to which base
layer 114 is
attached.
FIGS. 7 & 8 depict another embodiment of a process chamber 240 and associated
mixing structure, with FIG. 8 being a cross-sectional view taken along line 8-
8 in FIG. 7.
In this embodiment, the mixing stricture includes two mixing chambers 260a and
260b
(collectively referred to herein as mixing chambers 260). The mixing chambers
260 are
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located above the process chamber 240 such that at least a portion of each of
the process
chambers 260 is located between the process chamber 240 and one of the major
sides of
the sample processing device in which the process chamber 240 is located. As
such, the
mixing chambers 260 may be described as having portions that are located
within the
footprint of the process chamber 240, where the footprint of the process
chamber 240 is
defined as the projection of the process chamber 240 on a major side of the
sample
processing device along an axis that is normal to the major side. Although not
depicted, it
may be preferred that the mixing chamber or mixing chambers are located
completely
within the footprint of the process chamber 240.
One potential advantage of constructions in which portions or all of the
mixing
chamber or chambers are located within the footprint of the process chamber is
that the
mixing structure does not substantially enlarge the amount of area required on
the sample
processing device to provide a process chamber with mixing structure.
Because the mixing chambers 260 are located above the process chamber 240, the
are comlected thereto by mixing ports 262a and 262b that extend through mixing
layer 216
connected to the base layer 214. The process chamber 240 is defined in the
base layer 214
and also by a base cover layer 213 attached to the base layer 214. A cover
layer 218
attached to mixing layer 216 further defines the volumes of the mixing chamber
260.
The process chamber 240 includes an optional valve 244 with a valve septum 246
that is opened to allow sample material to flow into conduit 242 for delivery
to other
features that may be present on the sample processing device.
In addition, the mixing ports 262a and 262b also include optional valves in
the
form of septums 266a and 266b that must be opened to allow any sample material
in the
process chamber 240 to enter the one or both of the mixing chambers 260. The
septums
266a and 266b may be opened by any suitable technique used in connection with,
e.g.,
septum 246 of valve 244. The use of valves in connection with mixing chambers
260 may
be particularly useful if, e.g., the mixing chambers 260 include one or more
reagents
located therein and contact of those reagents and the sample material is to be
controlled.
As used herein and in the appended claims, the singular forms "a," "and," and
"the"
include plural referents unless the context clearly dictates otherwise. Thus,
for example,
reference to "a mixing chamber" includes a plurality of mixing chambers and
reference to
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"the process chamber" includes reference to one or more process chambers and
equivalents thereof known to those skilled in the art.
Illustrative embodiments of this invention are discussed and reference has
been
made to possible variations within the scope of this invention. These and
other variations
and modifications in the invention will be apparent to those skilled in the
art without
departing from the scope of the invention, and it should be understood that
this invention
is not limited to the illustrative embodiments set forth herein. Accordingly,
the invention
is to be limited only by the claims provided below and equivalents thereof.
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